%0 Journal Article
%T Back to the sea twice: identifying candidate plant genes for molecular evolution to marine life
%A Lothar Wissler
%A Francisco M Codo£żer
%A Jenny Gu
%A Thorsten BH Reusch
%A Jeanine L Olsen
%A Gabriele Procaccini
%A Erich Bornberg-Bauer
%J BMC Evolutionary Biology
%D 2011
%I BioMed Central
%R 10.1186/1471-2148-11-8
%X In our study, we provide the first quantitative perspective on molecular adaptations in two seagrass species. By constructing orthologous gene clusters shared between two seagrasses (Z. marina and P. oceanica) and eight distantly related terrestrial angiosperm species, 51 genes could be identified with detection of positive selection along the seagrass branches of the phylogenetic tree. Characterization of these positively selected genes using KEGG pathways and the Gene Ontology uncovered that these genes are mostly involved in translation, metabolism, and photosynthesis.These results provide first insights into which seagrass genes have diverged from their terrestrial counterparts via an initial aquatic stage characteristic of the order and to the derived fully-marine stage characteristic of seagrasses. We discuss how adaptive changes in these processes may have contributed to the evolution towards an aquatic and marine existence.Lambers and co-authors summarized the uniqueness of seagrasses as follows: "Aquatic angiosperms are perhaps comparable to whales: They returned to the water, preserving some features of terrestrial organisms" [1]. The monocotyledonous seagrasses represent, in fact, a polyphyletic group of plants that can live underwater in fully marine environments. At least three independent seagrass lineages, but no other angiosperm species, have evolved to a life in the marine environment [2,3].Seagrasses consist of about 60 species, most of which superficially resemble terrestrial grasses of the family Poaceae in that they have long, narrow leaves and grow in large meadows. Seagrasses belong to the order of Alismatales which includes 11 families of aquatic-freshwater species and 4 families that are fully marine. The marine families include the Posidoniaceae, Zosteraceae, Hydrocharitaceae, and Cymodoceaceae, and have originated in the Cretaceous period [2]. Phylogenetic analysis of members of the entire order, based on the plastid gene encoding for RuBi
%U http://www.biomedcentral.com/1471-2148/11/8